Influence of annealing temperature on the properties of In₂S₃:Sn films deposited by spray pyrolysis

Tin-doped In₂S₃ films were grown by the chemical spray pyrolysis method using compressed air as a carrier gas. The films were annealed for 2 h at different temperatures (300, 400 and 500 °C) under nitrogen atmosphere. X-ray diffraction data show that In₂S₃:Sn films are polycrystalline with a cubic phase. The film grain size increases from 26 to 37 nm. The residual microstrain and dislocation network reach the values 3.08 × 10⁻³ and 0.73 × 10¹¹ lines cm⁻², respectively, at the annealing temperature of 500 °C. Transmittance decreases with increasing temperature. It varies in the range of 65–85 % in visible and infrared regions. The optical band gap is found to vary in the range 2.4–2.85 eV for direct transitions. The best surface state is obtained at 400 °C. The RMS roughness was estimated to be 39.4–19.8 nm. Electrical measurements at room temperature show that the sheet resistance decreases down to 130 Ω at 500 °C. The conductance and capacitance characterization at ambient temperature are also investigated and give interesting physical properties for photovoltaic applications.